Volcanoes Pt. II

Question 1

increasing silicia = increasing viscosity = _____ explosivity

Answer 1

increasing

Question 2

mafic lava (basalt) explosivity? gases in magma can ____ easily

Answer 2

-less explosive (expect with water)
-escape

Question 3

the largest mountain on earth is typically what type of volcanoes?

Answer 3

shield

Question 4

shield volcanoes look like what?

Answer 4

shield upside down

Question 5

how do shield volcanoes form? type of magma?

Answer 5

-fluid basalt lava flow layer upon layer on low angle
-mafic

Question 6

how do cinder cones volcanoes form? type of magma?

Answer 6

-when gas-charged mafic lava ejects from single vent + breaks into fragments as it solidfies forming cinders which fall around vent,f orming cone
-mafic

Question 7

how do fissure volcanoes form? type of magma? where is it found?

Answer 7

-not from central vent
-mafic
-mid-ocean ridges -> formed flood basalts

Question 8

kimberlites (def.)

Answer 8

ultra-mafic rock; host of diamonds

Question 9

why are felsic/intermediate lava explosive?

Answer 9

high viscosity (very thick), gases in magma cannot easily escape as it rises to the surface quickly (produces large amounts of tephra and gas)

Question 10

how do stratovolcanoes (composite volcanoes) form? type of magma?

Answer 10

-produced by alternating lava, tephra, pyroclastic flow
-intermediate magmas (andesite) but can be anything

Question 11

major felsic eruptions can _____ volcano

Answer 11

-destroy

Question 12

how do lava domes form? type of magma?

Answer 12

-forms when erupting lava is too thick to flow, piling up to form domes; common in stratovolcanoes and help rebuild volcano after destruction
-intermediate

Question 13

how do calderas form? type of magma?

Answer 13

-very large craters in ground (not seen as volcano); formed when ground collaspses after magma chamber under volcano is drained
-felsic/intermediate

Question 14

subduction zones magma type? type of volcano?

Answer 14

-intermediate
-stratovolcanoes

Question 15

hot spot under ocean crust magma type? type of volcano?

Answer 15

-basalt
-shield volcanoes or fissures

Question 16

mid-ocean magma type? type of volcano?

Answer 16

-basalt
-fissures

Question 17

continental rifts magma type? type of volcano?

Answer 17

-varied
-varied

Question 18

hot spot under crust magma type? type of volcano?

Answer 18

-rhyolite
-calderas but also flood basalts

Question 19

what are seven volcanic hazards?

Answer 19

• lava flows
  -tephra/ash fall (explosive eruptions, hazard to people, planes, lungs)
  -pyroclastic flows (explosive eruptions or lava dome collapses- pompeii)
  -mudflows (lahars) (needs water source)
  -tsunamis/landslides
  -gas emissions (CO2, chlorine, fluoride, sulfur)
  -climate change

Question 20

what are the different time scales that volcanoes can impact climate? + type of volcanoes?

Answer 20

• large explosive eruptions -> short term cooling = strato/composite volcanoes)
• long term effusive eruptions (flood basalts)
• earth volcanoes help CO2 level in atmosphere (snowball earth)